need help
- Thread starter pthai
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I presume this hasn't always been the problem...
You need about 3" from the tips of the prop as clearance. What has changed? Can you send a few photos? Can you find a smaller diameter coupling? Can you raise the engine? What engine and boat are we talking about? Need more info and we'll be glad to help.
You need about 3" from the tips of the prop as clearance. What has changed? Can you send a few photos? Can you find a smaller diameter coupling? Can you raise the engine? What engine and boat are we talking about? Need more info and we'll be glad to help.
To clarify Jim's statement
Do a proper shaft alignment and the problem should be fixed. Is there no strut on this shaft? If the rear engine mounts were set too low or the front too high, then your coupling would be too low and your prop too high. I would be very carefull what you do here. I would start by disconnecting the shaft from the tranny and see where it wants to go naturally. After a few days it should settle in to a fairly normal position. Next align the engine to match the shaft. This must be done with the boat in the water. Tim R.
Do a proper shaft alignment and the problem should be fixed. Is there no strut on this shaft? If the rear engine mounts were set too low or the front too high, then your coupling would be too low and your prop too high. I would be very carefull what you do here. I would start by disconnecting the shaft from the tranny and see where it wants to go naturally. After a few days it should settle in to a fairly normal position. Next align the engine to match the shaft. This must be done with the boat in the water. Tim R.
clear the way
pthai; After doing what TimR suggests, if the coupling (which must not be stock) still contacts the inner hull, I think it would be OK to shave the hull down a bit with a Dremel. There's plenty of meat there and all you may need is a sixteenth or so groove.
pthai; After doing what TimR suggests, if the coupling (which must not be stock) still contacts the inner hull, I think it would be OK to shave the hull down a bit with a Dremel. There's plenty of meat there and all you may need is a sixteenth or so groove.
Regardless...
...of whether you shave down the high spot, clearly the motor mounts need adjustment. I'm surprised the engine hasn't been shaking from the alignment being out of whack. This fix is relatively easy but requires high tolerances to get it right. More in the Archives on "Engine alignment."
...of whether you shave down the high spot, clearly the motor mounts need adjustment. I'm surprised the engine hasn't been shaking from the alignment being out of whack. This fix is relatively easy but requires high tolerances to get it right. More in the Archives on "Engine alignment."
Sharft may be too short...
...if all other suggestions fail! *yks But, my first thought is that the engine needs alignment. If there is no strut, then, I think the original one must have been removed and the shaft is too short, now!
...if all other suggestions fail! *yks But, my first thought is that the engine needs alignment. If there is no strut, then, I think the original one must have been removed and the shaft is too short, now!
The boat is a beneteau 350,It had a yanmar 3gm engine untill recently and there was no problem with it. But the engine was changed to a yanmar tractor engine 3t72 and thats when the problem started ( I did not change the engine! ) and I have no strut so I can not align the engine to the shaft. I think the tractor engine is longer than the 3gm or the mounting bracket holes on it are higher or lower that the 3gm. The back mountings are as low as they can go ( I changed the two front last year and I have just put in two new back moubntings trying to fix this problem they did not but stopped some vibrating) but if I lift them the drive shaft hits the stern tube if I want to lower them I have to take of the nut and use washers to lift it! I will get photo but it will be sunday
Changes in latitudes-get a longer shaft
Since you changed to the longer tractor engine, everything has to change. You can't shorten the engine, but if you get a longer shaft, the latitude fo the prop will be lower.
Since you changed to the longer tractor engine, everything has to change. You can't shorten the engine, but if you get a longer shaft, the latitude fo the prop will be lower.
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